An object of the invention is to provide a power source circuit for a high frequency power amplifying circuit, which has excellent responsiveness of an output voltage and can be used for a portable telephone of the GSM or WCDMA system.
Another object of the invention is to provide a power source circuit for a high frequency power amplifying circuit, which can be used for a portable telephone capable of performing communications in two or more communication systems such as GSM and CDMA system and, moreover, has high power efficiency.
Further another object of the invention is to provide a power source circuit for a high frequency power amplifying circuit, which can contribute to smaller size and lighter weight of a portable telephone.
The above and other objects and novel features of the present invention will be apparent from the description of the specification and the appended drawings.
Representative ones of inventions disclosed in the specification will be briefly described as follows.
A power source circuit for a high frequency power amplifying circuit is constructed by using both a first direct current power source circuit such as a series regulator whose power efficiency is not high but which becomes the high level quickly, and a second direct current power source circuit such as a switching regulator, which does not become the high level quickly but whose power efficiency is high. When the power source voltage has to become the high level at high speed, both of the series regulator and the switching regulator are simultaneously operated. When the output power source voltage reaches a predetermined level, the operation of the series regulator is stopped.
The above-described means can be used for a portable telephone performing communications in the GSM and WCDMA requiring high-speed start of the power source of the high frequency power amplifying circuit. The series regulator is turned on for extremely short time immediately after start of the power source and it is sufficient to operate only the switching regulator during transmission operation as the most part. Therefore, the power efficiency can be increased largely as compared with a power source circuit constructed only by the series regulator.
In the case of applying the present invention to a power source circuit for a high frequency power amplifying circuit in a portable telephone capable of performing communications in two or more communication systems such as the GSM and CDMA, in both of operations in the GSM mode and the CDMA mode, an operation voltage can be supplied from a common power source circuit and it is unnecessary to provide a smoothing capacitor of large capacity.
Effects obtained by the representative ones of the inventions disclosed in the specification will be briefly described as follows.
According to the invention, two regulators of different characteristics are used and the regular which starts quickly is operated upon start. Thus, the power source circuit for a high frequency power amplifying circuit, which has excellent responsiveness of an output voltage and can be used for a portable telephone of the GSM or WCDMA system can be realized.
According to the invention, only the switching regulator is operated during transmission operation as the most part except for the time of start. Thus, the power source circuit for a high frequency power amplifying circuit having high power efficiency can be realized.
Further, according to the invention, operation voltage can be supplied from a common power source circuit and it is unnecessary to provide a smoothing capacitor of large capacity. Therefore, the power source circuit for a high frequency power amplifying circuit, which can contribute to reduction in size and weight of a portable telephone can be realized.